This invention constitutes an improvement over the oil supply reservoir disclosed in U.S. Pat. No. 4,947,963 granted on Aug. 14, 1990 to W. V. Aho, Jr., the co-inventor of this patent application and assigned to United Technologies Corporation, the assignee common to this patent application.
As noted in this U.S. Pat. No. 4,947,963, supra, it is abundantly important that the quality of the lubrication oil for the moving parts of the engines for powering aircraft is extremely high. To this end it is customary to utilize a forced recirculation system that requires a sump reservoir from which oil is supplied, a pump and distribution lines for delivering the oil to and from the bearings and the like for their proper lubrication and cooling. The tank must contain sufficient oil so as to fill the lines of the distribution system during engine startup and so as to compensate for the oil which may be lost to leakage during operation.
In addition to being capable of continuously supplying oil to the bearing during any attitude of the aircraft throughout its operating envelope, the system must be vented to atmosphere to avoid excess pressure within the lubrication system.
The prior art system disclosed in this U.S. Pat. No. 4,947,963, supra, includes the swirl vessel apparatus disposed in the asymmetrically configured oil tank and consists of an ejector pump, means for multi-attitude operation and the network of supply and return lines for continuously drawing oil from the supply and returning the overflow oil to the oil tank. Essentially, the multi-attitude capability is provided by a plurality of oil make-up lines with inlet openings located in various locations so that any one of the lines will be in contact with the oil in the oil tank for any of the various attitudes. The ejector pump powered by the oil or the oil/air mixture is fluidly connected to each of these lines which serves by the Bernoulli effect to pump the oil from the makeup lines and tangentially inject the oil/air mixture into a cylindrical chamber to form a vortex so as to centrifuge the oil/air mixture for separating the air and oil components if there were any entrained air after having gone through a separate deaerator externally located upstream of the oil supply reservoir. The air is vented to atmosphere through a vent tube located centrally of the vortex chamber and the oil is continuously supplied to the distribution system by an outlet opening peripherally located in the vortex chamber.
While the system disclosed in U.S. Pat. No. 4,947,963, supra, is satisfactory for certain applications, we have found we can combine a deaerator function with the multi-attitude reservoir. This eliminates a separate deaerator component and reduces weight and pressure drop. Ejector performance and the air separation function of the deaerator is improved by providing a wake separator disposed in the flow path located at the entrance of the ejector. The wake separator separates a higher percentage of air that is entrapped in the oil in comparison to heretofore known oil supply systems so as to meet the requirements of current day aircraft applications. In one embodiment the separated air from the wake separator is judiciously discharged into the vortex chamber of the deaerator for removing any entrapped oil in the air, and in another embodiment the air from the wake separator is vented directly into the portion of the vent line where there is some vortex action. In the latter embodiment an annular dam-like member is disposed between the vent outlet and the outlet of the wake separator to prevent any entrapped oil in the wake separator discharge to migrate to the vent outlet.
The wake separator of this invention includes a plurality of tubes judiciously mounted to traverse the flow stream ahead of the nozzles of the ejector pump in the inlet thereof and each tube includes a plurality of axially spaced holes on the downstream side of the tube and a fluid connecting conduit for tangentially discharging the separated air into the vortex chamber or in a judicious location in the vent. The tubes are oriented in the inlet of the vortex generator to maximize on the air separation.
Additionally, it is essential that the pressure losses in the system be held to a minimum as any pressure losses would require larger components to generate the power to overcome those loses which, in turn, would add to the overall weight of the system which is directly equated into engine performance deficits. The ejector pump disclosed in the U.S. Pat. No. 4,947,963, supra, is unsatisfactory in certain respects because it is not as efficient as it might otherwise be. To this end the ejector pump casing in accordance with this invention is discretely configured into a scroll configuration for tangentially directing fluid into the ejector chamber and the flat plate ejectors are eccentrically mounted relative to the central axis of the ejector chamber such that the volume from the inlet of the scroll to the end of the casings annular manifold is progressively lessened to define a convergent passageway to enhance the entry into the nozzles of the ejector pump, and provide an even distribution of pressure and flow to all of the ejectors so that they can operate at the same efficiency and hence, improve overall efficiency as compared with heretofore known devices.
The foregoing and other features of the present invention will become more apparent from the following description and accompanying drawings.